Method of making a golf ball with a multi-layer, core

ABSTRACT

A multilayer golf ball including a solid center having a center hardness, a plurality of laminates cut into a plurality of shapes formed around the center to create an inner ball, and a cover formed around the inner ball, wherein the plurality of layers can include at least a first layer having a hardness greater than the center hardness and a second layer having a hardness greater than the first layer hardness, and optionally a third layer disposed between the first and the second layers having a hardness greater than the first layer hardness.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is divisional of U.S. patent application Ser.No. 09/948,692, filed Sep. 10, 2001, now pending, which is acontinuation-in-part of the U.S. patent application Ser. No. 09/172,608,filed Oct. 15, 1998, now U.S. Pat. No. 6,302,808, which is a divisionalof U.S. patent application Ser. No. 08/943,932, filed Oct. 3, 1997, nowU.S. Pat. No. 6,056,842, and also a continuation-in-part of U.S. patentapplication Ser. No. 09/630,387, filed Aug. 1, 2000, which is acontinuation-in-part of U.S. patent application Ser. No. 08/603,057,filed Feb. 16, 1996, now U.S. Pat. No. 5,759,676, and acontinuation-in-part of U.S. patent application Ser. No. 08/996,718,filed Dec. 23, 1997, now U.S. Pat. No. 6,124,389, which is acontinuation-in-part of U.S. patent application Ser. No. 08/746,362,filed Nov. 8, 1996, now U.S. Pat. No. 5,810,678, which is acontinuation-in-part of U.S. patent application Ser. No. 08/706,008,filed Aug. 30, 1996, now U.S. Pat. No. 5,813,923, which is acontinuation-in-part of U.S. patent application Ser. No. 08/603,057,filed Feb. 16, 1996, now U.S. Pat. No. 5,759,676, which is acontinuation-in-part of U.S. patent application Ser. No. 08/482,522,filed Jun. 7, 1995, now U.S. Pat. No. 5,688,191, the disclosures ofwhich are hereby incorporated by reference in their entirety.

FIELD OF THE INVENTION

[0002] The present invention is directed to a method for making amultilayer golf ball including a solid center having a center hardness,a plurality of laminates cut into a plurality of shapes formed aroundthe center to create an inner ball, and a cover formed around the innerball, wherein the plurality layers can include at least a first layerhaving a hardness greater than the center hardness and a second layerhaving a hardness greater than the first layer hardness, and optionallya third intermediate layer disposed between the first and the secondintermediate layers having a hardness greater than the first layerhardness. This invention also relates to a multilayer golf ball having acore, a cover and a plurality of intermediate layers disposed betweenthe core and cover, wherein the intermediate layers are formed fromthermoplastic or thermoset materials. The multilayer golf balls of thepresent invention have been found to provide the distance and durabilitycharacteristics approaching that of a conventional two piece ball whilealso providing the feel and “click” similar to that of a conventionalwound golf ball.

BACKGROUND OF THE INVENTION

[0003] Golf ball manufacturers constantly strive to construct golf ballswith a balance of good “feel,” distance, and durability. Adjusting theconstruction of the ball, e.g., multilayer, and/or the composition ofthe individual layers, e.g., high flexural modulus material in anintermediate layer, allows golf ball manufacturers to tweak ballproperties to obtain the desired balance of golf ball properties.

[0004] Golf balls today can be of varied construction, e.g., two pieceballs, three piece balls, the latter including wound balls. Thedifference in play characteristics resulting from these different typesof constructions can be quite significant.

[0005] Generally, golf balls have been classified as solid or woundballs. Solid balls having a two piece construction, typically ancrosslinked rubber core, e.g., polybutadiene crosslinked with zincdiacrylate and/or similar crosslinking agents, encased by a blendedcover, e.g., ionomer resins, are generally most popular with the averagerecreational golfer. The combination of the core and cover materialsprovide a “hard” ball that is virtually indestructible by golfers andone that imparts a high initial velocity to the ball, resulting inimproved distance. Because the materials of which the ball is formed arevery rigid, two piece balls have a hard “feel” when struck with a club.Likewise, due to their hardness, these balls have a relatively low spinrate which provides greater distance.

[0006] Wound balls are generally constructed from a liquid or solidcenter surrounded by tensioned elastomeric material and covered with adurable cover material, e.g., ionomer resin, or a softer cover material,e.g., balata or polyurethane. Wound balls are generally thought of asperformance golf balls and have good resiliency, desirable spincharacteristics, and feel when struck by a golf club. However, woundballs are generally difficult to manufacture when compared to solid golfballs.

[0007] The prior art includes a variety of golf balls that have beendesigned to provide particular playing characteristics. Thesecharacteristics are generally the initial velocity and spin of the golfball, which can be optimized for various types of players. For instance,certain players prefer a ball that has a high spin rate in order tocontrol and stop the golf ball. Other players prefer a ball that has alow spin rate and high resiliency to maximize distance. Generally, agolf ball having a hard core and a soft cover will have a high spinrate. Conversely, a golf ball having a hard cover and a soft core willhave a low spin rate. Golf balls having a hard core and a hard covergenerally have very high resiliency for distance, but are hard feelingand difficult to control around the greens. A number of patents, forexample, have been issued which are directed towards improving the carrydistance of conventional two piece balls by altering the typical singlelayer core and single cover layer construction to provide a multi-layerball, e.g., a dual cover layer, dual core layer, and/or a ball having anintermediate layer disposed between the cover and the core. U.S. Pat.Nos. 4,863,167, 5,184,828, and 4,714,253 are examples of such multilayergolf balls.

[0008] In addition, there are a number of patents directed to improvingthe spin, click and feel of solid balls while maintaining the distanceprovided by the solid construction golf balls. U.S. Pat. Nos. 5,072,944,4,625,964, 4,650,193, and 4,848,770 disclose a golf ball having a rubbercore and intermediate layer, e.g., polybutadiene, surrounded by a cover.U.S. Pat. Nos. 5,253,871, 5,681,898, 5,439,227, 5,556,098 are directedto golf balls having intermediate layers using a variety of materialsother than polybutadiene.

[0009] Further, there are also several patents which are directed togolf balls having multiple cover layers. U.S. Pat. Nos. 4,431,193,5,314,187, 4,919,434 are examples of such patents.

[0010] It would be advantageous to provide a golf ball having a core, aplurality of solid intermediate layers, and a cover, wherein thematerials included in the intermediate layers are the same or different,resulting in a golf ball having improved physical properties.

SUMMARY OF THE INVENTION

[0011] The present invention is directed to an improved golf ball,including a core having a center and multiple layers, to improve theplaying characteristics of the golf ball. The invention includes a golfball having a core, wherein the core includes a center having a firsthardness and a diameter of about 1 inch or less, and at least threelayers surrounding the center having a thickness of about 0.1 inches orless, and a cover surrounding the core. The three layers and the centerpreferably include a thermoset rubber, e.g., polybutadiene rubber, eachhaving a unique hardness different from the other core layers.

[0012] The present invention is also directed to a golf ball including acore, a cover, and at least one intermediate layer disposed between thecore and the cover, wherein the intermediate layer is formed from acomposition including at least one thermoplastic or thermosetpolyurethane material, and wherein the golf ball has a compression ofabout 75 to about 85. In a preferred embodiment, the cover has ahardness of about 60 to about 72 Shore D.

[0013] In one embodiment, the intermediate layer has a hardness ofbetween about 35 and 60 Shore D. In another embodiment, the coverhardness and the intermediate layer hardness have a first ratio fromabout 1.2 to about 2.1. In still another embodiment, the core has ahardness such that a second ratio of the intermediate layer hardness tothe core hardness is about 0.64 to about 0.91. In a preferredembodiment, the core hardness is less than about 80 Shore C.

[0014] Preferably, the intermediate layer has a Shore D hardness ofabout 37 to about 45 and a flexural modulus of about 10,000 psi orgreater. In one embodiment, the composition is solely thermoplasticpolyurethane material. In another embodiment, the intermediate layercomposition further includes an ethylene methacrylic/acrylic acidcopolymer.

[0015] In another embodiment, the intermediate layer further includesadditional thermoplastic material selected from the group consisting ofpolyesterester block copolymers, polyetherester block copolymers,polyetheramide block copolymers, ionomer resins, dynamically vulcanizedthermoplastic elastomers, styrene-butadiene elastomers with functionalgroups such as maleic anhydride or sulfonic acid attached, thermoplasticpolyesters, polymers formed using a metallocene catalyst, and mixturesthereof. Preferably, the thermoplastic or thermoset polyurethanematerial is present in an amount from about 25 to about 75 percent byweight.

[0016] In still another embodiment, the composition further includes asecond thermoplastic or thermoset polyurethane.

[0017] Preferably, the intermediate layer has a thickness of about 0.125inches or less. In another embodiment, the intermediate layer has aspecific gravity of about 1.14 or greater. In a preferred embodiment,the intermediate layer has a specific gravity of greater than about 1.2.

[0018] In yet another embodiment, the composition further includes adensity-adjusting filler. Preferably, the filler includes bariumsulfate, zinc oxide, titanium dioxide, and mixtures thereof. If a filleris present, it preferably includes zinc oxide present in an amount fromabout 5 to about 40 weight percent.

[0019] In another embodiment, the core has a specific gravity of about 1to about 1.2. In one embodiment, the core has a diameter of about 1.51inches or less. In still another embodiment, the core has a Shore Chardness of about 80 or less. Preferably, the core includes a blend ofpolybutadiene and calcium oxide, and the at least one intermediate layeris formed of a composition including polyurethane material present in anamount of about 25 to about 75 weight percent, copolymer of ethylene andmethacrylic acid present in an amount from about 10 to about 50 weightpercent, and zinc oxide present in an amount from about 20 to about 30weight percent. In one embodiment, the cover includes a blend of atleast one ionomer.

[0020] The present invention is also directed to a golf ball including acore, a cover, and at least one intermediate layer disposed between thecore and the cover, wherein the core has a hardness of less than about80 Shore C; and the intermediate layer is formed from a blend includinga thermoplastic polyurethane material, wherein the golf ball has acompression of about 75 to about 85, and wherein the intermediate layerhas a hardness of between about 35 and about 50 Shore D. Preferably, thecover has a hardness of about 60 to about 72 Shore D.

[0021] In one embodiment, the core has a Bashore resilience of betweenabout 30 to about 80. Preferably, the core resilience is between about40 and about 70. In another embodiment, the intermediate layer has aBashore resilience of between about 35 and about 75. Preferably, theintermediate layer resilience is between about 60 and about 70.

[0022] The present invention is also directed to a golf ball including asolid core, an intermediate layer, and a cover, wherein the solid corehas a diameter of between about 1.25 and about 1.51 inches and aspecific gravity of between about 1 and about 1.2, wherein theintermediate layer includes a polyurethane resin and has a hardness ofbetween about 20 and about 60 Shore D and a specific gravity of greaterthan about 1.2 and greater than that of the solid core, and wherein thecover includes an ionomer resin and has a thickness about 0.04 inches orgreater and a hardness of between about 60 and about 72 Shore D.

[0023] In one embodiment, the core diameter is between about 1.3 andabout 1.48 inches. In another embodiment, the intermediate layer has aspecific gravity of between about 1.21 and about 1.3. Preferably, theintermediate layer has a specific gravity of between about 1.23 andabout 1.29. In another embodiment, the cover thickness is between about0.04 and about 0.41 inches. In still another embodiment, theintermediate layer has a thickness of between about 0.02 and about 0.125inches. In a preferred embodiment, the intermediate layer has a diameterof between about 1.27 and about 1.64 inches.

[0024] The present invention is also directed to a golf ball having[will add once new claims are finalized]

BRIEF DESCRIPTION OF THE DRAWINGS

[0025]FIG. 1 is a cross-sectional view of a golf ball formed accordingto the present invention;

[0026]FIG. 2 is a perspective view of a laminate including three layersof core material;

[0027]FIG. 3 is a sectional view of rollers and material being formedinto the laminate of core material;

[0028]FIG. 4 is a sectional view of a mold for forming multiple layersabout a core center according to the present invention;

[0029]FIG. 5 is a sectional view of a mold forming multiple layers abouta core center according to the invention with the mold-forming sheetsbeing vacuum formed within the mold;

[0030]FIG. 6 is a sectional view of a mold forming multiple layers abouta core center according to the invention with the mold-forming sheetsbeing vacuum formed within the mold;

[0031]FIG. 7 is a perspective view of a half mold for use in formingmultiple layers about core centers according to the present invention;

[0032]FIG. 8 is a cross-sectional view of a compression mold of a golfball core according to the present invention;

[0033]FIG. 9 is an exploded view of a golf ball core according to thepresent invention in a retractable-pin injection mold;

[0034]FIG. 10 is a cross-sectional view of a golf ball core according tothe present invention in a retractable-pin injection mold;

[0035]FIG. 11 is a cross-sectional view of a golf ball according to thepresent invention in a retractable-pin mold; and

[0036]FIG. 12 is an exploded view of a golf ball core according to thepresent invention with cover layer hemispheres in a compression mold.

DETAILED DESCRIPTION OF THE INVENTION

[0037] The present invention is directed to multilayer golf balls havinga core and a cover and at least one intermediate layer therebetween,resulting in excellent playing characteristics, e.g., resiliency, spinrates and feel. In particular, the present invention relates to golfballs having at least one of the following features: multiple corelayers with an improved concentricity; intermediate layers formed from athermoplastic or thermoset polyurethane; and a plurality of intermediatelayers, wherein each intermediate layer is formed from a thermoplasticor thermoset materials.

[0038]FIG. 1 shows a multilayer golf ball according to one embodiment ofthe present invention. Golf ball 10 includes a center 11, a first layer12, a second layer 13, a third layer 14, and a cover 15. The first,second, and third layers may be of the same or different material. Asused herein, the term “core layer” means any layer surrounding thecenter of the ball, but not the outermost layer, and, therefore, theterm may be used interchangeably with the term “intermediate layer.”

[0039] As used herein, the term “layer” includes any generally sphericalportion of a golf ball or golf ball core, center, intermediate, orcover, including a one-piece ball. An “intermediate layer” is definedherein as a portion of the golf ball that occupies a volume between thecover and the core. Of course, as one of ordinary skill in the art wouldrecognize, any of the core, cover, and intermediate of the golf balls ofthe invention can be formed of one layer or a plurality of layers, asthat term is defined herein.

[0040] As used herein, the term “multilayer” means at least two layersand includes fluid-center balls, hollow-center balls, and balls with atleast two intermediate layers and/or cover layers.

[0041] The following terms that are used in this application are definedin terms of the enumerated ASTM tests: Specific gravity ASTM D - 297¹Flexural (Flex) Modulus ASTM D - 6272-98, Procedure B Shore C & DHardness ASTM D - 2240-00 Melt flow index ASTM Test D 1238, Condition E,Procedure A

[0042] The Center

[0043] The golf balls of the present invention are formed with a centerhaving a low compression, but still exhibit a finished ball COR andinitial velocity approaching that of conventional two-piece distanceballs. Preferably, the center employed in the golf balls of the presentinvention have a compression of about 60 or less, more preferably about45 to about 60 and most preferably about 50 to about 55. As used herein,the term “about,” used in connection with one or more numbers ornumerical ranges, should be understood to refer to all such numbers,including all numbers in a range. Likewise, it is preferred that thefinished balls made with such centers have a COR, measured at an inboundspeed of 125 ft./s., of about 0.795 to about 0.815, more preferablyabout 0.797 to about 0.812 and most preferably about 0.800 to about0.810.

[0044] As used herein, “COR” refers to Coefficient of Restitution, whichis obtained by dividing a ball's rebound velocity by its initial (i.e.,incoming) velocity. This test is performed by firing the samples out ofan air cannon at a vertical steel plate over a range of test velocities(from 75 to 150 ft/s). A golf ball having a high COR dissipates asmaller fraction of its total energy when colliding with the plate andrebounding therefrom than does a ball with a lower COR. Unless otherwisenoted, the COR values reported herein are the values determined at anincoming velocity of 125 ft/s.

[0045] In a preferred embodiment, the center has a Shore C hardness ofabout 65 to about 80, more preferably about 68 to about 75 and mostpreferably about 72 to about 75.

[0046] The centers employed in the golf balls of the present inventionpreferably have a diameter of about 1.25 inches to about 1.51 inches,more preferably about 1.30 inches to about 1.48 inches and mostpreferably about 1.39 inches. The overall diameter of the center and theintermediate layer is about 84 percent to about 97 percent of theoverall diameter of the finished ball.

[0047] A representative base composition for forming the centersemployed in the present invention includes polybutadiene and, in partsby weight based on 100 parts polybutadiene, 20 to 50 parts of a metalsalt diacrylate, dimethacrylate, or monomethacrylate, preferably zincdiacrylate. The polybutadiene preferably has a cis-1,4 content of aboveabout 90 percent and more preferably above about 96 percent. Commercialsources of polybutadiene include Shell 1220 manufactured by ShellChemical, NEOCIS® BR40 manufactured by Enichem Elastomers, and UBEPOL®BR150 manufactured by Ube Industries, Ltd. If desired, the polybutadienecan also be mixed with other elastomers known in the art, such asnatural rubber, styrene butadiene, and/or isoprene in order to furthermodify the properties of the center. When a mixture of elastomers isused, the amounts of other constituents in the center composition areusually based on 100 parts by weight of the total clastomer mixture.

[0048] Metal salt diacrylates, dimethacrylates, and monomethacrylatessuitable for use in the center employed in this invention include thosewherein the metal is magnesium, calcium, zinc, aluminum, sodium, lithiumor nickel. Zinc diacrylate is preferred, because it provides golf ballswith a high initial velocity in the United States Golf Association(“USGA”) test. The zinc diacrylate can be of various grades of purity.For the purposes of this invention, the lower the quantity of zincstearate present in the zinc diacrylate the higher the zinc diacrylatepurity. Zinc diacrylate containing less than about 10 percent zincstearate is preferable. More preferable is zinc diacrylate containingabout 4 to about 8 percent zinc stearate. Suitable, commerciallyavailable zinc diacrylates include those from Rockland React-Rite andSartomer. The preferred concentrations of zinc diacrylate that can beused are 20 to 50 parts per hundred (pph) based upon 100 pph ofpolybutadiene or alternately, polybutadiene with a mixture of otherelastomers that equal 100 pph. As used herein, the term “pph” inconnection with a batch formulation refers parts by weight of theconstituent per hundred parts of the base composition.

[0049] Free radical initiators are used to promote cross-linking of themetal salt diacrylate, dimethacrylate, or monomethacrylate and thepolybutadiene. Suitable free radical initiators for use in the inventioninclude, but are not limited to peroxide compounds, such as dicumylperoxide; 1,1-di(t-butylperoxy) 3,3,5-trimethyl cyclohexane; bis(t-butylperoxy) diisopropylbenzene; 2,5-dimethyl-2,5 di (t-butylperoxy)hexane; or di-t-butyl peroxide; and mixtures thereof. Other usefulinitiators would be readily apparent to one of ordinary skill in the artwithout any need for experimentation. The initiator(s) at 100 percentactivity are preferably added in an amount ranging between about 0.05and about 2.5 pph based upon 100 parts of butadiene, or butadiene mixedwith one or more other elastomers. More preferably, the amount ofinitiator added ranges between about 0.15 and about 2 pph and mostpreferably between about 0.25 and about 1.5 pph.

[0050] Typical prior art golf ball centers incorporate 5 to 50 pph ofzinc oxide (ZnO) in a zinc diacrylate-peroxide cure system thatcross-links polybutadiene during the core molding process. However, inthe present invention it is preferred that the ZnO in the centercomposition is eliminated in favor of calcium oxide (CaO). Centersproduced from an admixture containing CaO have been found to exhibitdesirable performance properties. In particular, when ZnO is replacedwith CaO, it has been observed that the initial velocity and COR of thecenter is maintained, but the compression of the center is reduced by atleast about 4 compression points on the standard compression scale, andmay be reduced as much as 6 points.

[0051] As used herein, the terms “points” or “compression points” referto the compression scale or the compression scale based on the ATTIEngineering Compression Tester. This scale, which is well known to thoseworking in this field, is used in determining the relative compressionof a center or ball. Some artisans use the Reihle compression scaleinstead of the standard compression scale. Based on disclosure in U.S.Pat. No. 5,368,304, column 20, lines 55-53 it appears that Reihlecompression values can be converted to compression values through theuse of the following equation:

compression value=160−Reihle compression value.

[0052] Additionally, the combination of the use of calcium oxide and ahigher percentage of zinc diacrylate can be used to maintain the samecompression as with the zinc oxide, but the initial velocity and COR issignificantly increased. Thus, by using calcium oxide, either the centercompression can be lowered and the initial velocity and COR maintainedor the amount of zinc diacrylate can be increased so that the centercompression is the same and the initial velocity and COR is increased.

[0053] The amount of calcium oxide added to the center-formingcomposition may be from about 0.1 to about 15, preferably 1 to 10, mostpreferably 1.25 to 5, parts calcium oxide per hundred parts ofpolybutadiene.

[0054] The center compositions employed in the present invention mayalso include fillers, added to the elastomeric composition to adjust thedensity and/or specific gravity of the center. As used herein, the term“fillers” includes any compound or composition that can be used to varythe density and other properties of the subject golf ball center.Fillers useful in the golf ball center according to the presentinvention include, for example, zinc oxide (in an amount significantlyless than that which would be necessary without the addition of thecalcium oxide), barium sulfate, and regrind (which is recycled coremolding matrix ground to 30 mesh particle size). The amount and type offiller utilized is governed by the amount and weight of otheringredients in the composition, since a maximum golf ball weight of1.620 oz has been established by the USGA. Appropriate fillers generallyused range in specific gravity from about 2.0 to about 5.6. In thepreferred golf ball, the amount of filler in the center is lower thanthat of a typical golf ball such that the specific gravity of the centeris decreased.

[0055] The preferred range of specific gravities of the centers employedin the present invention is from about 1.0 to about 1.2, more preferablyin the range of about 1.1 to about 1.18, depending upon the size of thecenter, cover, intermediate layer and finished ball, as well as thespecific gravity of the cover and intermediate layer.

[0056] Other ingredients such as accelerators, e.g. tetra methylthiuram,processing aids, processing oils, plasticizers, dyes and pigments,antioxidants, as well as other additives well known to the skilledartisan may also be used in the present invention in amounts sufficientto achieve the purpose for which they are typically used.

[0057] The Intermediate Layer(s)

[0058] The intermediate layer(s) may be formed from dynamicallyvulcanized thermoplastic elastomers, functionalized styrene-butadieneelastomers, thermoplastic rubbers, thermoset elastomers, thermoplasticurethanes, metallocene polymers, thermoset urethanes, ionomer resins, orblends thereof. In a preferred embodiment of the present invention, theintermediate layer includes a thermoplastic or thermoset polyurethane.

[0059] Suitable dynamically vulcanized thermoplastic elastomers includeSANTOPRENE®, SARLINK®, VYRAM®, DYTRON® and VISTAFLEX®. SANTOPRENE® isthe trademark for a dynamically vulcanized PP/EPDM. SANTOPRENE® 203-40is an example of a preferred SANTOPRENE® and is commercially availablefrom Advanced Elastomer Systems.

[0060] Examples of suitable functionalized styrene-butadiene elastomers,i.e., styrene-butadiene elastomers with functional groups such as maleicanhydride or sulfonic acid, include KRATON FG-1901×and FG-1921×, whichare available from the Shell Corporation of Houston, Tex.

[0061] Examples of suitable thermoplastic polyurethanes include ESTANE®58133, ESTANE® 58134 and ESTANE® 58144, which are commercially availablefrom the B. F. Goodrich Company of Cleveland, Ohio.

[0062] Suitable metallocene polymers, i.e., polymers formed with ametallocene catalyst include those commercially available from SentinelProducts of Hyannis, Mass. Suitable thermoplastic polyesters includepolybutylene terephthalate.

[0063] Suitable thermoplastic ionomer resins are obtained by providing across metallic bond to polymers of monoolefin with at least one memberselected from the group consisting of unsaturated mono- or di-carboxylicacids having 3 to 12 carbon atoms and esters thereof (the polymercontains 1 to 50 percent by weight of the unsaturated mono- ordi-carboxylic acid and/or ester thereof). More particularly, low modulusionomers such as acid-containing ethylene copolymer ionomers, includeE/X/Y copolymers where E is ethylene, X is a softening comonomer such asacrylate or methacrylate present in 0-50 (preferably 0-25, mostpreferably 0-2), weight percent of the polymer, and Y is acrylic ormethacrylic acid present in 5-35 (preferably 10-35, most preferably15-35, making the ionomer a high acid ionomer) weight percent of thepolymer, wherein the acid moiety is neutralized 1-90 percent (preferablyat least 40 percent, most preferably at least about 60 percent) to forman ionomer by a cation such as lithium*, sodium*, potassium, magnesium*,calcium, barium, lead, tin, zinc* or aluminum (*=preferred), or acombination of such cations. Specific acid-containing ethylenecopolymers include ethylene/acrylic acid, ethylene/methacrylic acid,ethylene/acrylic acid/n-butyl acrylate, ethylene/methacrylicacid/n-butyl acrylate, ethylene/methacrylic acid/iso-butyl acrylate,ethylene/acrylic acid/iso-butyl acrylate, ethylene/methacrylicacid/n-butyl methacrylate, ethylene/acrylic acid/methyl methacrylate,ethylene/acrylic acid/methyl acrylate, ethylene/methacrylic acid/methylacrylate, ethylene/methacrylic acid/methyl methacrylate, andethylene/acrylic acid/n-butyl methacrylate. Preferred acid-containingethylene copolymers include ethylene/methacrylic acid, ethylene/acrylicacid, ethylene/methacrylic acid/n-butyl acrylate, ethylene/acrylicacid/n-butyl acrylate, ethylene/methacrylic acid/methyl acrylate andethylene/acrylic acid/methyl acrylate copolymers. The most preferredacid-containing ethylene copolymers are ethylene/methacrylic acid,ethylene/acrylic acid, ethylene/(meth)acrylic acid/n-butyl acrylate,ethylene/(meth)acrylic acid/ethyl acrylate, and ethylene/(meth)acrylicacid/methyl acrylate copolymers.

[0064] Such ionomer resins include SURLYN® and lotek®, which arecommercially available from DuPont and Exxon, respectively.

[0065] In another preferred embodiment of the present invention, theintermediate layer is a blend of a first and a second component whereinthe first component is a dynamically vulcanized thermoplastic elastomer,a functionalized styrene-butadiene elastomer, a thermoplastic orthermoset polyurethane or a metallocene polymer and the second componentis a material such as a thermoplastic or thermoset polyurethane, athermoplastic polyetherester or polyetheramide, a thermoplastic ionomerresin, a thermoplastic polyester, another dynamically vulcanizedelastomer, another a functionalized styrene-butadiene elastomer, anothera metallocene polymer or blends thereof. In a more preferred embodiment,at least one of the first and second components includes a thermoplasticor thermoset polyurethane.

[0066] Such thermoplastic blends useful in the intermediate layers ofthe golf ball of the present invention preferably include about 1percent to about 99 percent by weight of a first thermoplastic and about99 percent to about 1 percent by weight of a second thermoplastic.Preferably the thermoplastic blend includes about 5 percent to about 95percent by weight of a first thermoplastic and about 5 percent to about95 percent by weight of a second thermoplastic. In a preferredembodiment of the present invention, the first thermoplastic material ofthe blend is a dynamically vulcanized thermoplastic elastomer, such asSantoprene®.

[0067] The intermediate layer of the present invention may be formedfrom an intermediate layer blend including up to 100 percent by weightof an ethylene methacrylic/acrylic acid copolymer. As used herein, theterm “copolymer” refers to a polymer which is formed from two or moremonomers. Below is a non-limiting example of the chemical structure forsuitable ethylene methacrylic/acrylic acid copolymers:

[0068] wherein

[0069] x=50 to 99 percent;

[0070] y=1 to 50 percent;

[0071] z=O to 49 percent;

[0072] R₁═H or CH₃; R₂═CH₃ or isobornyl; and

[0073] n=0 to 12.

[0074] Specific acid-containing ethylene copolymers includeethylene/acrylic acid; ethylene/methacrylic acid; ethylene/acrylicacid/n- or isobutyl acrylate; ethylene/methacrylic acid/n- or iso-butylacrylate; ethylene/acrylic acid/methyl acrylate; ethylene/methacrylicacid/methyl acrylate; ethylene/acrylic acid/iso-bornyl acrylate ormethacrylate and ethylene/methacrylic acid/isobornyl acrylate ormethacrylate. Suitable ethylene methacrylic/acrylic acid copolymers aresold commercially by DuPont under the tradename NUCREL®, with NUCREL®960, NUCREL® RX9-1, and 010 being preferred.

[0075] In one embodiment, the intermediate layer is formed from a blendwhich includes an ethylene methacrylic/acrylic acid copolymer.

[0076] In another embodiment of the present invention, the intermediatelayer is formed from a blend which includes an ethylenemethacrylic/acrylic acid copolymer and a second component which includesa thermoplastic material. Suitable thermoplastic materials for use inthe intermediate blend include, but are not limited to, polyesteresterblock copolymers, polyetherester block copolymers, polyetheramide blockcopolymers, ionomer resins, dynamically vulcanized thermoplasticelastomers, styrene-butadiene elastomers with functional groups such asmaleic anhydride or sulfonic acid attached, thermoplastic polyurethanes,thermoplastic polyesters, polymers formed using a metallocene catalyst(“metallocene polymers”) and/or blends thereof.

[0077] Suitable thermoplastic polyetheresters include materials whichare commercially available from DuPont under the tradename HYTREL® andinclude HYTREL® 3078, HYTREL® G3548W and HYTREL® G4078W.

[0078] Suitable thermoplastic polyetheramides are commercially availablefrom Elf-Atochem of Philadelphia, Pa., under the tradename PEBAX® andinclude PEBAX® 2533, PEBAX® 1205 and PEBAX® 4033.

[0079] Preferably, the second component of the intermediate layer blendincludes polyetherester block copolymer, with HYTREL® 3078 being aparticularly preferred polyetherester block copolymer.

[0080] Other conventional materials, such as balata, elastomer andpolyethylene may also be used in the first, second and third layers 12,13 and 14 of the present invention.

[0081] Many prior art intermediate layers generally have a specificgravity of about 1 or less. However, in a preferred embodiment, theintermediate layer employed in the golf balls of the present inventionhave a specific gravity greater than 1.2, preferably about 1.21 to about1.30, more preferably about 1.23 to about 1.29 and most preferably about1.27.

[0082] The desired specific gravity of the intermediate layer may beobtained by adding a filler such as barium sulfate, zinc oxide, titaniumdioxide and combinations thereof to the intermediate layer blend. Zincoxide is the preferred filler.

[0083] In one embodiment of the present invention, the intermediatelayer is formed from a blend of about 1 to about 99 percent by weightethylene methacrylic/acrylic acid copolymer, about 0 to about 75 percentby weight of the second thermoplastic component (as described above) andabout 0 to about 50 percent by weight zinc oxide. In another embodimentof the present invention, the intermediate layer is formed from a blendof about 10 to 50 percent by weight ethylene methacrylic/acrylic acidcopolymer, 25 to 75 percent by weight of a second thermoplasticcomponent and about 5 to about 40 percent by weight zinc oxide. In amost preferred embodiment of the present invention, the intermediatelayer is formed from a blend of about 15 to about 25 percent by weightethylene methacrylic/acrylic acid copolymer, about 50 to about 60percent by weight of a second thermoplastic component and about 20 toabout 30 percent by weight zinc oxide. In another embodiment of theinvention, the second thermoplastic component is present in theintermediate layer blend in an amount of less than 50 percent by weight,and preferably 30 to 45 percent by weight. A specific example of thisembodiment is an intermediate layer composition including about 57percent by weight HYTREL® 3078, about 20 percent by weight NUCREL® 960,and about 23 percent by weight zinc oxide.

[0084] The intermediate layer blend preferably has a flexural modulus ofless than about 10,000 psi, more preferably about 5,000 to about 8,000psi and most preferably about 7,500 psi. Likewise, the intermediatelayers employed in the golf balls of the present invention preferablyhave a Shore D hardness of about 35 to 50, more preferably about 37 toabout 45 and most preferably about 40.

[0085] Preferably, the intermediate layer and core construction employedin the present invention have a compression of less than about 65, morepreferably about 50 to about 65, and most preferably about 50 to 55.

[0086] The intermediate layer employed in the golf balls of the presentinvention preferably have a thickness from about 0.020 inches to about0.125 inches, more preferably about 0.035 inches to about 0.085 inchesand most preferably about 0.06 inches The outer diameter of theintermediate layer is preferably about 1.510 inches.

[0087] The golf balls of the present invention may include a pluralityof intermediate layers, e.g., a first intermediate layer adjacent thecore and a second intermediate layer adjacent the cover. The firstintermediate layer may include the materials as discussed above.Preferably, the first intermediate layer includes a thermoplasticmaterial and has a greater hardness than the core. The secondintermediate layer may be disposed around the first intermediate layerand preferably has a greater hardness than the first intermediate layer.

[0088] The second intermediate layer may be formed of materials such aspolyether or polyester thermoplastic urethanes, thermoset urethanes, andionomers such as acid-containing ethylene copolymer ionomers, includingE/X/Y terpolymers where E is ethylene, X is an acrylate ormethacrylate-based softening comonomer present in 0 to 50 weight percentand Y is acrylic or methacrylic acid present in 5 to 35 weight percent.More preferably, in a low spin rate embodiment designed for maximumdistance, the acrylic or methacrylic acid is present in 15 to 35 weightpercent, making the ionomer a high modulus ionomer.

[0089] In one embodiment, the second intermediate layer is formed ofcomposition including at least one high acid ionomer. As used herein,the term “high acid ionomer”, is an ionomer resin wherein Y is acrylicor methacrylic acid units present from about 17 weight percent to about35 weight percent in the polymer. Generally, a high acid ionomer willhave a Shore D hardness of about 60 or greater and a flexural modulus ofabout 50,000 psi or greater, preferably from about 50,000 psi to about125,000 psi. In the vernacular of the golf ball art, high acid ionomersare sometimes referred to as “hard” ionomers.

[0090] In another embodiment, the second intermediate layer ispreferably formed of a thermoset material, preferably having a flexuralmodulus of about 50,000 psi or greater. In one embodiment, the thermosetmaterial is polybutadiene.

[0091] In one embodiment, the second intermediate layer is adjacent thecover and has a hardness greater than that of the first intermediatelayer.

[0092] A third intermediate layer may be disposed in between the firstand second intermediate layers. The third intermediate layer may beformed of the variety of materials as discussed above. In oneembodiment, the third intermediate layer is disposed in between thefirst and second intermediate layers and preferably has a hardnessgreater than the hardness of the first intermediate layer.

[0093] The Cover Layer

[0094] The cover layer of the present invention may include at least onelayer of a thermoplastic or thermosetting material. Any number of a widevariety of cover materials may be used in the present invention such asionomer resins, polyurethanes, balata and blends thereof.

[0095] In one embodiment, the cover is formed of a composition includingvery low modulus ionomers (VLMIs). As used herein, the term “very lowmodulus ionomers”, or the acronym “VLMIs”, are those ionomer resinsfurther including a softening comonomer X, commonly a (meth)acrylateester, present from about 10 weight percent to about 50 weight percentin the polymer. VLMIs are copolymers of an α-olefin, such as ethylene, asoftening agent, such as n-butyl-acrylate or iso-butyl-acrylate, and anα,β-unsaturated carboxylic acid, such as acrylic or methacrylic acid,where at least part of the acid groups are neutralized by a magnesiumcation. Other examples of softening comonomers include n-butylmethacrylate, methyl acrylate, and methyl methacrylate. Generally, aVLMI will have a flexural modulus from about 2,000 psi to about 10,000psi. VLMIs are sometimes referred to as “soft” ionomers. U.S. Pat. No.6,144,415, which is incorporated in its entirety by reference herein,discloses suitable VLMIs for incorporation into the cover formulationsof the present invention.

[0096] Ionomers, such as acid-containing ethylene copolymer ionomers,include E/X/Y copolymers where E is ethylene, X is a softening comonomersuch as acrylate or methacrylate present in 0 to 50 (preferably 0 to 25,most preferably 0 to 2), weight percent of the polymer, and Y is acrylicor methacrylic acid present in 5 to 35 (preferably 10 to 35, mostpreferably 15 to 20) weight percent of the polymer, wherein the acidmoiety is neutralized 1 to 90 percent (preferably at least 40 percent,most preferably at least about 60 percent) to form an ionomer by acation such as lithium, sodium, potassium, magnesium, calcium, barium,lead, tin, zinc or aluminum, or a combination of such cations, lithium,sodium and zinc being the most preferred. Specific acid-containingethylene copolymers include ethylene/acrylic acid, ethylene/methacrylicacid, ethylene/acrylic acid/n-butyl acrylate, ethylene/methacrylicacid/n-butyl acrylate, ethylene/methacrylic acid/iso-butyl acrylate,ethylene/acrylic acid/iso-butyl acrylate, ethylene/methacrylicacid/n-butyl methacrylate, ethylene/acrylic acid/methyl methacrylate,ethylene/acrylic acid/methyl acrylate, ethylene/methacrylic acid/methylacrylate, ethylene/methacrylic acid/methyl methacrylate, andethylene/acrylic acid/n-butyl methacrylate. Preferred acid-containingethylene copolymers include ethylene/methacrylic acid, ethylene/acrylicacid, ethylene/methacrylic acid/n-butyl acrylate, ethylene/acrylicacid/n-butyl acrylate, ethylene/methacrylic acid/methyl acrylate andethylene/acrylic acid/methyl acrylate copolymers. The most preferredacid-containing ethylene copolymers are ethylene/methacrylic acid,ethylene/acrylic acid, ethylene/(meth)acrylic acid/n-butyl acrylate,ethylene/(meth)acrylic acid/ethyl acrylate, and ethylene/(meth)acrylicacid/methyl acrylate copolymers.

[0097] As mentioned above, ionomer resins are commercially availablefrom E. I. DuPont de Nemours and Co. of Wilmington, Del., under thetradename SURLYN®, and from Exxon Corporation of Houston, Tex., underthe tradename IOTEK®. Some particularly suitable SURLYN® include SURLYN®8140 (Na) and SURLYN® 8546 (Li) which have an methacrylic acid contentof about 19 percent.

[0098] To aid in the processing of the cover stock, and as is well knownin the art, ionomer resins may be blended in order to obtain a coverhaving desired characteristics. For this reason, it is preferable thatthe covers of the golf balls of the present invention be formed from ablend of two or more ionomer resins. A particularly preferred covermaterial for use in the present invention is formed from a blend ofabout 50 percent by weight SURLYN® 7940, about 47 percent by weightSURLYN® 8940 and about 3 percent by weight SURLYN® 8660.

[0099] In one embodiment, the cover material includes a blend of a verysoft material and a harder material. Preferably, the cover includesabout 75 to about 25 parts by weight based on 100 parts by weight resin(pph) of a VLMI and about 25 pph to about 75 pph of a standard ionomerresin. Preferably, the VLMI is a sodium ionomer resin and constitutesabout 40 pph to about 60 pph of the ionomer blend and the standardionomer resin is a lithium ionomer resin and constitutes about 60 pph toabout 40 pph of the ionomer blend. Even more preferably, a 50/50 blendof the sodium and lithium ionomers with additives, e.g., colorconcentrate, is used for the cover composition. Suitable sodium ionomerresins include, but are not limited to SURLYN® 8320, SURLYN® 8269, andSURLYN® 8265.

[0100] The sodium ionomer resin is preferably a copolymer includingabout 95 to about 80 parts by weight of copolymer of ethylene and about5 to about 12 parts by weight of the copolymer of acrylic or methacrylicacid in which about 10 percent to about 90 percent of the acid groupsare neutralized by sodium. In one embodiment, the sodium ionomer resinused in the present invention has a flexural modulus between about 1,000and about 20,000 psi (5 and 140 MPa) and, more preferably, between about2,000 and about 10,000 psi (10 to 70 MPa).

[0101] The lithium ionomer resin is preferably a copolymer includingabout 95 to about 80 parts by weight of ethylene and about 10 to about16 parts by weight of acrylic or methacrylic acid based on 100 parts byweight copolymer. Preferably, the lithium ionomer resin has about 10percent to about 90 percent of the acid groups neutralized by lithium.Preferably, the lithium ionomer resin has a high flexural modulus whichis above about 60,000 psi (415 MPa). More preferably, the lithiumionomer resin used in the present invention has a flexural modulusbetween about 60,000 and about 80,000 psi (415 and 550 MPa). Goodresults have been obtained with the lithium ionomer resins havingflexural moduli in the range of about 60,000 psi to about 70,000 psi(415 to 485 MPa), e.g., SURLYN® 8118, SURLYN® 7930 and SURLYN® 7940.

[0102] Both the lithium and sodium ionomer resins preferably have about10 percent to about 90 percent of their carboxylic acid groupsneutralized by their respective metal ions. More preferably, both thelithium and sodium ionomer resins have their carboxylic acid groupsneutralized about 35 percent to about 65 percent by the metal ion.Preferably, the VLMI and harder ionomer resins include the samemonocarboxylic acid, e.g. either methacrylic or acrylic acid.

[0103] In order to adjust the characteristics of the cover stock, otherionomer resins besides sodium and lithium can be employed.

[0104] SURLYN® 8320, SURLYN® 8269 and SURLYN® 8265 have flexural moduliof 2,800 psi (20 MPa), 2,800 psi (20 MPa) and 7,100 psi (50 MPa),respectively. SURLYN® 8118, 7930 and 7940 have flexural moduli of 61,000psi (420 MPa), 67,000 psi (460 MPa) and 61,000 psi (420 MPa)respectively.

[0105] Conventionally, ionomer resins with different melt flow indexesare employed to obtain the desired characteristics of the cover stock.SURLYN® 8118, 7930 and 7940 have melt flow indices of about 1.4, 1.8,and 2.6 g/10 min., respectively. SURLYN® 8269 and SURLYN® 8265 both havea melt flow index of about 0.9 g/10 min. Preferably, the blend ofionomer resins used to make a cover of a golf ball in accordance withthe present invention has a melt flow index between about 1 to about 4g/10 min. and, more preferably, about 1 to about 3 g/10 min.

[0106] The combined amount of lithium ionomer resin and sodium ionomerresin used to make a cover in accordance with this embodiment of thepresent invention as described generally makes up at least about 90percent by weight of the total weight of the golf ball cover and,preferably, at least about 95 percent by weight. Additional materialswhich may be included in the golf ball cover are other SURLYN® resins;whitening agents such as titanium dioxide; dyes; UV absorbers; opticalbrighteners; and other additives which are conventionally included ingolf ball covers.

[0107] In another embodiment, the cover composition includes at leasttwo ionomer resins, preferably sodium ionomer resin and lithium ionomerresin, having similar flexural moduli. Preferably, the sodium ionomerresin is a copolymer including about 95 to about 80 parts by weight ofcopolymer of ethylene and about 12 to about 20 parts by weight of thecopolymer of acrylic or methacrylic acid in which about 10 percent toabout 90 percent of the acid groups are neutralized by sodium.

[0108] Preferably, the lithium ionomer resin is a copolymer includingabout 95 to about 80 parts by weight of ethylene and about 12 to about20 parts by weight of acrylic or methacrylic acid based on 100 parts byweight copolymer. Preferably, the lithium ionomer resin has about 10percent to about 90 percent of the acid groups neutralized by lithium.

[0109] Preferably, the sodium ionomer resin used in the presentinvention has a flexural modulus between about 60,000 and about 80,000psi (415 and 550 MPa).

[0110] The lithium ionomer resin used in the present invention has aflexural modulus between about 60,000 and about 80,000 psi (415 and 550MPa). Good results have been obtained with the sodium and lithiumionomer resins having flexural moduli in the range of about 60,000 psito about 70,000 psi (415 to 485 MPa).

[0111] Preferably, the ionomer resins incorporate the samemonocarboxylic acid, e.g., either methacrylic or acrylic acid.

[0112] Sodium ionomer resin sold by DuPont under the name SURLYN® 8920has worked well in the present invention. Good results have also beenobtained with a lithium ionomer resin sold under the trade name SURLYN®7940 by DuPont.

[0113] The cover layer employed in the present invention preferably havea Shore D hardness of about 60 to about 72, more preferably about 65 toabout 70 and most preferably about 68 to about 70.

[0114] Castable reactive liquid materials are particularly preferred forthe cover layers of the balls of the present invention. As used herein,the term “castable reactive liquid material” may refer to thermoset orthermoplastic materials. In a preferred embodiment, the castablereactive liquid material is a thermoset material.

[0115] In one embodiment, the castable reactive liquid material is casturethane or polyurethane. Polyurethane is a product of a reactionbetween a polyurethane prepolymer and a curing agent. The polyurethaneprepolymer is a product formed by a reaction between a polyol and adiisocyanate. Often a catalyst is employed to promote the reactionbetween the curing agent and the polyurethane prepolymer. In the case ofcast polyurethanes, the curing agent is typically either a diamine orglycol.

[0116] In another preferred embodiment, the castable reactive liquidmaterial is a thermoset cast polyurethane. Thermoset cast polyurethanesare generally prepared using a diisocyanate, such as 2,4-toluenediisocyanate (TDI), methylenebis-(4-cyclohexyl isocyanate) (HMDI), orpara-phenylene diisocyanate (“PPDI”) and a polyol which is cured with apolyamine, such as methylenedianiline (MDA), or a trifunctional glycol,such as trimethylol propane, or tetrafunctional glycol, such asN,N,N′,N′-tetrakis(2-hydroxpropyl)ethylenediamine. However, any suitablecast or non-cast thermoset polyurethane may be employed to form outercover layers of the present invention.

[0117] Other suitable thermoset materials contemplated for the coverlayers include, but are not limited to, thermoset urethane ionomers andthermoset urethane epoxies. Examples of suitable thermoset polyurethaneionomers are disclosed in U.S. Pat. Nos. 5,334,673 and 5,692,974, whichare incorporated in their entirety by reference herein. Other examplesof thermoset materials include polybutadiene, natural rubber,polyisoprene, styrene-butadiene, or styrene-propylene-diene rubber,which are particularly suitable when used in an intermediate layer of agolf ball.

[0118] When the cover includes more than one layer, e.g., an inner coverlayer and an outer cover layer, various constructions and materials aresuitable. For example, as disclosed in U.S. Pat. Nos. 5,803,831 and6,210,293, which are incorporated in their entirety by reference herein,an inner cover layer may surround the intermediate layer with an outercover layer disposed thereon or an inner cover layer may surround aplurality of intermediate layers.

[0119] When using an inner and outer cover layer construction, the outercover layer material is preferably a thermoset material that includes atleast one of a castable reactive liquid material and reaction productsthereof, as described above, and preferably has a hardness from about 30Shore D to about 60 Shore D. In one embodiment, the outer cover layer isthin, preferably less than about 0.05 inches, and more preferably fromabout 0.02 inches to about 0.045 inches.

[0120] The inner cover layer may be formed from a wide variety of hard(about 65 Shore D or greater, preferably from about 69 Shore D to about74 Shore D), high flexural modulus resilient materials, which arecompatible with the other materials used in the adjacent layers of thegolf ball. The inner cover layer materials preferably has a flexuralmodulus of about 65,000 psi or greater. In one embodiment, the flexuralmodulus of the inner cover layer material is from about 70,000 psi toabout 120,000 psi.

[0121] Suitable inner cover layer materials include the hard, highflexural modulus ionomer resins and blends thereof as disclosed in U.S.Pat. No. 5,885,172, which is incorporated in its entirety by referenceherein. These ionomers are obtained by providing a cross metallic bondto polymers of monoolefin with at least one member selected from thegroup consisting of unsaturated mono- or di-carboxylic acids having 3 to12 carbon atoms and esters thereof (the polymer contains 1 to 50 percentby weight of the unsaturated mono- or di-carboxylic acid and/or esterthereof). More particularly, such acid-containing ethylene copolymerionomer component includes E/X/Y copolymers where E is ethylene, X is asoftening comonomer such as acrylate or methacrylate present in 0-50(preferably 0-25, most preferably 0-20), weight percent of the polymer,and Y is acrylic or methacrylic acid present in 5-35 (preferably atleast about 16, more preferably at least about 16-35, most preferably atleast about 16-20) weight percent of the polymer, wherein the acidmoiety is neutralized 1-90 percent (preferably at least 40 percent, mostpreferably at least about 60 percent) to form an ionomer by a cationsuch as lithium*, sodium*, potassium, magnesium*, calcium, barium, lead,tin, zinc* or aluminum (*=preferred), or a combination of such cations.Specific acid-containing ethylene copolymers include ethylene/acrylicacid, ethylene/methacrylic acid, ethylene/acrylic acid/n-butyl acrylate,ethylene/methacrylic acid/n-butyl acrylate, ethylene/methacrylicacid/iso-butyl acrylate, ethylene/acrylic acid/iso-butyl acrylate,ethylene/methacrylic acid/n-butyl methacrylate, ethylene/acrylicacid/methyl methacrylate, ethylene/acrylic acid/methyl acrylate,ethylene/methacrylic acid/methyl acrylate, ethylene/methacrylicacid/methyl methacrylate, and ethylene/acrylic acid/n-butylmethacrylate. Preferred acid-containing ethylene copolymers includeethylene/methacrylic acid, ethylene/acrylic acid, ethylene/methacrylicacid/n-butyl acrylate, ethylene/acrylic acid/n-butyl acrylate,ethylene/methacrylic acid/methyl acrylate and ethylene/acrylicacid/methyl acrylate copolymers. The most preferred acid-containingethylene copolymers are ethylene/methacrylic acid, ethylene/acrylicacid, ethylene/(meth)acrylic acid/n-butyl acrylate,ethylene/(meth)acrylic acid/ethyl acrylate, and ethylene/(meth)acrylicacid/methyl acrylate copolymers.

[0122] Examples of other suitable inner cover materials includethermoplastic or thermoset polyurethanes, polyetheresters,polyetheramides, or polyesters, dynamically vulcanized elastomers,functionalized styrene-butadiene elastomers, metallocene polymers,polyamides such as nylons, acrylonitrile butadiene-styrene copolymers(ABS), or blends thereof. Suitable thermoplastic polyetheresters includematerials which are commercially available from DuPont under thetradename Hytrel®. Suitable thermoplastic polyetheramides includematerials which are available from Elf-Atochem under the tradenamePebax®.

[0123] The multi-layer golf ball of the invention can have an overalldiameter of any size. Although the United States Golf Associationspecifications limit the minimum size of a competition golf ball to1.680 inches in diameter or more, there is no specification as to themaximum diameter. Moreover, golf balls of any size can be used forrecreational play. The preferred diameter of the present golf balls isfrom about 1.680 inches to about 1.800 inches. The more preferreddiameter is from about 1.680 inches to about 1.760 inches. The mostpreferred diameter is about 1.680 inches to about 1.740 inches.

[0124] The golf balls of the present invention have an overall maximumcompression of about 85, preferably about 75 to about 85, morepreferably about 80 to about 85 and most preferably about 82.

[0125] Golf Ball Assembly

[0126] The center 11, as shown in FIG. 1, is preferably formed bycompression molding a sphere from a prep of center material. Compressionmolding solid centers is well known in the art.

[0127] In one embodiment, the golf ball of the present invention may beformed with a laminate process, as shown in FIGS. 2 and 3. In order toform multiple layers around the center according to this embodiment ofthe invention, a laminate 20 is first formed. The laminate 20 includesat least two layers and, preferably, three layers 22, 23, 24. In oneembodiment, the laminate is formed by mixing uncured core material to beused for each layer and calendar rolling the material into thin sheets32, 33, 34. In another embodiment, the laminate is formed by mixinguncured intermediate layer material and rolling the material into sheets32, 33, 34. The laminate sheets 32, 33, 34 are stacked together to formthe laminate 20 having three layers 22, 23, 24 using calender rollingmills. In another embodiment, however, the sheets 32, 33, 34 are made byextrusion.

[0128] In an alternate embodiment, the laminate 20 can be furtherconstructed using an adhesive between each layer of material.Preferably, an epoxy resin such as Epoxy Resin #1028 from RBC Industriesin Warwick, R1 is used. The adhesive should have good shear and tensilestrength and, preferably the adhesive should have a tensile strengthover about 1500 psi. Still further, the adhesive should not becomebrittle when cured. An adhesive having a Shore D hardness of less than60 when cured is preferred. The adhesive layer applied to the sheetsshould be very thin and preferably, less than 0.004 inches thick.

[0129] Preferably, each laminate sheet is formed to a thickness that isslightly larger than the thickness of the layers 12, 13, 14 in thefinished golf ball 10. Each of these thicknesses can be varied, but allhave a thickness of preferably less than about 0.1 inches. Preferably,the sheets are formed to thicknesses that are less than 0.05 inches andthe laminate thickness is less than 0.15 inches. The sheets 32, 33 and34 should have very uniform thicknesses, i.e., the thickness of eachsheet should not vary more than about 0.005 inches.

[0130] The next step in the method, as shown in FIGS. 4-7, is to formmultiple layers around the center. This is preferably accomplished byplacing two laminates 20, 21 in between a top mold 36 and a bottom mold37, as illustrated in FIG. 4. The molds 36, 37 are formed of mold frames38 and replaceable mold halves 39 such as that described in U.S. Pat.No. 4,508,309 to Brown, the disclosure of which is incorporate in itsentirety by reference herein. The laminates 20, 21 are formed to thecavities in the mold halves 39.

[0131] In one embodiment, the laminates 20, 21 are cut into patternsthat, when joined, form a laminated layer around the center 11. Forexample, as illustrated in FIG. 5, the laminates 20, 21 may be cut intofigure 8-shaped or barbell-like patterns, similar to a baseball or atennis ball cover. Other patterns, such as curved triangles,hemispherical cups, ovals, or any like patterns that may be joinedtogether to form a laminated layer around the center 11 may also beused. The patterns may then be placed in between molds 36, 37 and formedto the cavities in the mold halves 39.

[0132] In one embodiment, the laminates are suction formed to thecavities by using a vacuum source 40. The vacuum source 40 suction formsthe laminates 20, 21 to the half mold cavities 39 so that uniformity inlayer thickness is maintained.

[0133] After the laminates 20, 21 have been formed to the cavities,centers 11 are then inserted between the laminates, as shown in FIG. 6.The laminates 20, 21 are then compression molded about the center 11under conditions of temperature and pressure that are well known in theart.

[0134] The half molds 39 have a plurality of vents 41, as shown in FIGS.7 and 8. The compression molding step includes flowing excess layermaterial from the laminates 20, 21 through at least three vents 41 sothat the flow of laminate material is symmetrical about the center 11and so that the center 11 does not shift due to lateral flow patterns.In a preferred embodiment, the half molds 39 have 4 to 6 vents.

[0135] The next step in the present invention is to form a cover 15around the golf ball core 16, i.e., the inner components of the golfball. The core 16, including center 11 and layers 12, 13, 14, issupported within a pair of cover mold-halves 50, 51 by a plurality ofretractable pins 52, as shown in FIG. 9. The retractable pins 52 areactuated by conventional means known to those of ordinary skill in theart of mold design.

[0136] After the mold-halves 50, 51 are closed together with the pins 52supporting the core 16, the cover material is injected into the mold ina liquid state through a plurality of injection ports or gates 49, asshown in FIG. 10. Gates 49 can be edge gates or sub-gates. With edgegates, the resultant golf balls are all interconnected and may beremoved from the mold-halves 50, 51 together in a large matrix.Sub-gating automatically separates the mold runner from the golf ballsduring the ejection of the golf balls from mold-halves 50, 51.

[0137] As illustrated in FIG. 11, retractable pins 52 are retractedafter a predetermined amount of cover material has been injected intothe mold-halves 50, 51. The predetermined amount of cover material issubstantially all of the material to be injected. Thus, the core 16 issubstantially surrounded by cover material and does not shift when theretractable pins 52 are removed. This allows the liquid cover materialto flow and substantially fill the cavity between the core 16 and themold-halves 50, 51. At the same time, concentricity is maintainedbetween the core 16 and the mold-halves 50, 51.

[0138] The cover material is allowed to solidify around the core 16,thereby forming cover 15. Golf ball 10 is then ejected from mold-halves50, 51, and finished using processes which are well known in the art.The temperatures and curing time for mold-halves 50, 51 are generallyknown in the art and are dependent on the material that is being usedfor cover 15.

[0139] In another embodiment, shown in FIG. 12, the cover 15 is formedusing cover layer hemispheres 55, 56. Two cover layer hemispheres 55, 56are pre-formed of the desired cover material, preferably, by aninjection molding process. The hemispheres 55, 56 are positioned aroundthe core 16, thereby forming an assembly 57. Assembly 57 is placed intoa compression mold 58 that includes two compression mold-halves 53, 54.Mold-halves 53, 54 are advanced toward each other until their matingsurfaces touch, and the mold 58 is heated to melt the hemispheres.Mold-halves 53, 54 compress and heat the hemispheres 55, 56 about thecore 16 to mold the cover material thereto.

[0140] While the embodiments above are directed to the use of laminatesto form the golf balls of the present invention, the construction of thegolf balls of the present invention are not limited to the embodimentsdescribed above and can be made by any conventional processes employedin the golf ball art. For example, the solid cores can be eitherinjection or compression molded. The intermediate layer may then besubsequently injection or compression molded about the core. It isimportant that the intermediate layer material be able to sustain thetemperatures applied during the application of the cover layer. Thecover layer or layers may then be injection or compression molded orcast about the intermediate layer.

[0141] Specific Golf Ball Constructions

[0142] Various embodiments of the golf balls are outlined below. Thegolf balls of the invention, however, variation of these embodiments arecovered as well. Properties such as hardness, Bayshore resilience,flexural modulus, center diameter, and layer thickness of the golf ballsof the present invention have been found to affect play characteristicssuch as spin, initial velocity and feel of golf balls.

[0143] In one embodiment, the center 11 and each of the layers 12, 13,14 are formed of a thermoset rubber, such as polybutadiene rubber. Inthis embodiment, a golf ball core 16 has a center 11 and three layers12, 13 and 14. The center diameter should be greater than about 1 inchand, preferably, should be about 1.25 to 1.45 inches. The most preferredcenter has a diameter of about 1.4 inches. Each of the layerssurrounding the center should have a thickness of less than about 0.1inches and preferably, less than about 0.05 inches. The most preferredthickness of the layers is about 0.03 to about 0.05 inches where thethickness of the third layer is equal to or less than the thickness: ofthe first and second layers. Moreover, the center 11 of the golf ballpreferably has an outer diameter of greater than 60 percent of thefinished ball 10 diameter. Most preferably, the center 11 has a diameterthat is at least 75 percent of the diameter of the finished-ball 10.

[0144] A small center of 1 inch or less and relatively thick corelayers, each having a thickness of greater than 0.1 inches, decreasesball initial velocity and reduces the ball spin rate effects. Whenimpacting a golf ball with different clubs within a set, the impactspeed and the impact angle are changed. On an average, for a tourprofessional the impact speed of a driver is about 110 miles an hour.The average professional 5 iron impact speed is around 90 miles an hourand the wedge impact velocity is less than about 80 miles an hour.Moreover, the force on the golf ball must be broken up into twocomponents, the normal force that is normal to the club face and thetangential force that is parallel to the club face. Since mostprofessionals use a driver having a loft of about 10 degrees, thetangential force is significantly less than the normal force. However,when using a wedge having a loft between 48 and 60 degrees, thetangential force becomes very significant. For example, experimentaldata shows that with a clubhead having an impact velocity of about 95miles an hour and an angle of 20 degrees, a two piece ball has a maximumdeflection of about 0.151 inches. When hit with a clubhead at 95 milesan hour and an impact angle of 40 degrees, the ball has a maximumdeflection of about 0.128 inches or a difference of 0.023 inches. Thus,the impact deflection depends significantly on the impact angle, and byhaving outer layers of less than 0.1 inches, the spin characteristics ofthe ball is altered for different clubs within a set as discussed inmore detail below.

[0145] For a high spin rate ball that also has good driver trajectorycharacteristics, the center 11 of the golf ball should have a Shore Chardness of about 70 or less. The first layer 12 should be harder thanthe center 11 and should have a Shore C hardness of about 70 to about75. The second layer 13 should be harder than the first layer 12 andhave a Shore C hardness of about 72 to about 77. The third layer orouter layer 14 should be harder than the second layer 13 and have aShore C hardness of about 75 to about 80. The cover 15 of the firstembodiment golf ball should be a soft cover and have a Shore D of lessthan 60. Moreover, the center 11, layers 12, 13 and 14 and the cover 15should be configured to provide a golf ball compression of less than 85and more preferably, less than about 80.

[0146] By creating a core 16 with relatively thin outer layers thatprogressively get harder, the spin rate of the ball is surprisingly goodfor a player that desires a high spin rate golf ball. More particularly,when this type of player hits the ball with a short iron, only the outerlayer and cover affect the spin rate of the ball. By incorporating avery hard core outer layer and a soft cover, the spin rate is maximizedfor the short iron shot such as a wedge having an angle of about 48 to60 degrees. In order to reduce the spin rate a little for middle ironshots such as a 6 iron having aloft of about 32 degrees to make surethat sufficient distance is obtained, the second layer is softer thanthe third layer. Similarly, to decrease the spin rate, provide gooddistance and a good trajectory for long irons such as a 3 iron having aloft of about 20 degrees, the first layer 11 is softer than the secondlayer 12. Finally, for a low spin rate with the driver having a loft ofabout 8 to 12 degrees, the center is made very soft.

[0147] Solid cores having diameters of about 1.58 inches may also bemade using the compositions of the core materials outline above. Coreshaving the centers as defined above preferably have a compression ofabout 50. The first layer composition preferably has a compression ofabout 75. Preferably, the first layer material will have a compressionthat is over 25 percent greater than the center material compression.The second layer composition preferably has a compression of about 85and, thus, has a greater compression than the first layer. The thirdlayer composition has a compression of about 110, which is significantlygreater than the second layer. Preferably, the third layer compressionis more than 75 percent greater than the center material compression.

[0148] In a preferred embodiment, the cover material includes a blend oftwo materials, a very soft material and a harder material. Preferably,the cover includes about 75 to about 25 parts by weight based on 100parts by weight resin (phr) of a low flexural modulus ionomer resin; andabout 25 to about 75 pph of a standard ionomer resin. The low flexuralmodulus ionomer is preferably a sodium ionomer resin and constitutesabout 40 pph to about 60 pph of the ionomer blend and the standardflexural ionomer is a lithium ionomer resin and constitutes about 60 pphto about 40 pph of the ionomer blend. The sodium ionomer resin ispreferably a copolymer including about 95 to about 80 parts by weight ofcopolymer of ethylene and about 5 to about 12 parts by weight of thecopolymer of acrylic or methacrylic acid in which about 10% to about 90%of the acid groups are neutralized by sodium. Preferably, lithiumionomer resin is a copolymer including about 95 to about 80 parts byweight of ethylene and about 10 to about 16 parts by weight of acrylicor methacrylic acid based on 100 party by weight copolymer. Preferably,the lithium ionomer resin has about 10 percent to about 90 percent ofthe acid groups neutralized by lithium.

[0149] Preferably, the low flexural modulus sodium ionomer resin used inthis embodiment has a flexural modulus between about 1,000 psi and about20,000 psi (5 MPa and 140 MPa) and, more preferably, between about 2,000psi and about 10,000 psi (10 MPa to 70 Mpa). The lithium ionomer resinpreferably has a high flexural modulus which is above about 60,000 psi(415 MPa). More preferably, the lithium ionomer resin used in thepresent invention has a flexural modulus between about 60,000 and about80,000 psi (415 and 550 MPa). Good results have been obtained with thelithium ionomer resins having flexural moduli in the range of about60,000 psi to about 70,000 psi (415 to 485 MPa).

[0150] In this embodiment, both the lithium and sodium ionomer resinspreferably have about 10 percent to about 90 percent of their carboxylicacid groups neutralized by their respective metal ions. More preferably,both the lithium and sodium ionomer resins have their carboxylic acidgroups neutralized about 35% to about 65% by the metal ion.

[0151] In addition, the ionomer resins preferably include the samemonocarboxylic acid, e.g. either methacrylic or acrylic acid.

[0152] In one embodiment, 55 weight percent SURLYN® 8320 and 45 weightpercent SURLYN® 7940 are included in the cover blend, wherein the blendhas a hardness of 55 Shore D. In another embodiment, 45 weight percentSURLYN® 8320 and 55 weight percent SURLYN® 7940 are included in thecover blend with a hardness of 59 Shore D.

[0153] In a second embodiment, the center 11 and each of the layers 12,13, 14 also include a thermoset rubber, such as polybutadiene.

[0154] In this second embodiment, the golf ball core also has a center11 and three layers 12, 13, 14. The center 11 should be greater than 1.0inch and, preferably, about 1.25 to 1.45 inches in diameter. The mostpreferred center has a diameter of about 1.4 inches. Each of the layersshould have a thickness of less than about 0.1 inches and preferably,less than about 0.05 inches. The most preferred thickness of each of thelayers is about 0.03 inches. Again, by having outer layers of less than0.1 inches, the spin characteristics of the ball can be altered fordifferent clubs within a set.

[0155] The center 11 of the second embodiment golf ball should have aShore C hardness of greater than about 75 for low swing speed players.The first layer should be softer than the center and have a Shore Chardness of about 75 to 72. The second layer should be softer than thefirst layer and have a Shore C hardness of about 73 to 70. The thirdlayer should be the softest and have a Shore C hardness of less thanabout 70. The cover of the second embodiment golf ball should have goodresilience and durability. Preferably, the cover of the secondembodiment is a harder cover and includes a blend of about 50/50 byweight of two standard or high acid ionomers. Standard ionomers haveabout 15 parts by weight of acrylic or methacrylic acid. High acidionomers have about 17 or more parts by weight of acrylic or methacrylicacid.

[0156] By creating a golf ball core 16 with relatively thin outer layersthat progressively get softer, the feel and distance is optimized for alow swing speed player. More particularly, when the low swing speedplayer hits the ball with a short iron, only the outer or third layerand cover are compressed. By utilizing a soft core and a harder cover,the feel of the ball is relatively soft when compared to distance ballshaving hard covers and hard cores. In order to increase the distance formiddle irons while still providing a relatively soft feel, the secondlayer is made harder than the third layer. Similarly, to provide greaterresiliency for long irons, the first layer 11 is harder than the secondlayer. Finally, for maximum resiliency with the driver, the center ismade harder than each of the layers. Since the center 11 is large, i.e.,between about 1.25 and 1.45 inches in diameter, the ball has a highcompression and initial velocity. However, since the third layer issoft, the ball provides a surprisingly better feel than hard core/hardcover balls.

[0157] Preferably, the cover material of this embodiment should providegood resiliency and durability. In one embodiment, the cover materialincludes of a blend of two ionomer resins having relatively the sameflexural moduli, e.g., sodium ionomer resin and lithium ionomer resin.

[0158] Preferably, the sodium ionomer resin is a copolymer includingabout 95 to about 80 parts by weight of copolymer of ethylene and about12 to about 20 parts by weight of the copolymer of acrylic ormethacrylic acid in which about 10 percent to about 90 percent of theacid groups are neutralized by sodium.

[0159] The lithium ionomer resin is preferably a copolymer includingabout 95 to about 80 parts by weight of ethylene and about 12 to about20 parts by weight of acrylic or methacrylic acid based on 100 parts byweight copolymer. Preferably, the lithium ionomer resin has about 10percent to about 90 percent of the acid groups neutralized by lithium.

[0160] Preferably, the sodium ionomer resin used according to thisembodiment preferably has a flexural modulus between about 60,000 andabout 80,000 psi (415 and 550 Mpa). The lithium ionomer resin usedaccording to this embodiment preferably has a flexural modulus betweenabout 60,000 and about 80,000 psi (415 and 550 MPa). Good results havebeen obtained with the sodium and lithium ionomer resins having flexuralmoduli in the range of about 60,000 psi to about 70,000 psi (415 to 485MPa).

[0161] Preferably, the ionomer resins incorporate the samemonocarboxylic acid, e.g., either methacrylic or acrylic acid.

[0162] Sodium ionomer resin sold by DuPont under the name SURLYN® 8920has worked well in the present invention. Good results have also beenobtained with a lithium ionomer resin sold under the trade name SURLYN®7940 by DuPont.

[0163] The golf ball of the present invention can have an overalldiameter of any size. Although the United States Golf Association (USGA)specifications limit the minimum size of a competition golf ball to morethan 1.680 inches in diameter, there is no specification as to themaximum diameter. Moreover, golf balls of any size can be used forrecreational play. The preferred diameter of the present golf balls isfrom about 1.680 inches to about 1.800 inches. The more preferreddiameter is from about 1.680 inches to about 1.760 inches. The mostpreferred diameter is about 1.680 inches to about 1.740 inches.

EXAMPLES Example 1

[0164] Table 1 sets forth an example of the core contents, i.e., centerand inner layers, according to one embodiment of the invention. Thefillers used in the compositions of these examples are regrind andbarium sulfate (BaSO₄). Vulcup 40KE® and Varox 231XL® are free radicalinitiators, and are a-a bis (t-butylperoxy) diisopropylbenzene and1,1-di (t-butylperoxy) 3,3,5-trimethyl cyclohexane, respectively. TABLE1 Core Compositions (pph, based on 100 parts of polybutadiene) Layer No.Center 1 2 3 Polybutadiene 100 100 100 100 Polywate 325 26 23 18 13Vulcup 40KE ® 0.3 0.3 0.3 0.3 Varox 231XL ® 0.6 0.5 0.5 0.5 BaSO₄ 31 2625 25 Zinc Diacrylate 30 32 35 47 SR-350 2 2 2 6 Calcium Oxide 3 0 0 0Zinc Oxide 0 3 6 6

[0165] The center 11 set forth in Table 1, has a Shore C hardness ofabout 65 at the center point thereof and a Shore C hardness of about 68at the midpoint between the center and the outer edge. The first layer12 is harder than the center 11 and has a Shore C hardness of about 71.The second layer 13 is harder than the first layer 12 and has a Shore Chardness of about 73. The third layer or outer layer 14 is harder thanthe second layer 13 and had a Shore C hardness of about 77. The cover 15of the first embodiment golf ball is a soft cover and includes a blendof about 50/50 by weight of very low flexural modulus ionomer and astandard ionomer. The golf ball preferably has a compression of about60.

[0166] The center 11 of the core 16 was compression molded to a diameterof about 1.39 inches and each of the three layers, 12, 13 and 14 had athickness of about 0.03 inches. Solid cores having diameters of about1.58 inches were made using the compositions of the core materials ofTable 1.

[0167] Cores having the center composition of Table 1 have a compressionof about 50. The first layer composition has a compression of about 75.The first layer material has a compression that is over 25 percentgreater than the center material compression. The second layercomposition has a compression of about 85 and, thus, has a greatercompression than the first layer. The third layer composition has acompression of about 110, which is significantly greater than the secondlayer. The third layer compression is more than 75 percent greater thanthe center material compression.

[0168] All the ingredients except the peroxides were mixed in a ProcessLab Brabender mixer to about 180-200° F. The peroxides were added in thesecond stage to the initial mixture, and the resulting mixture wasremoved from the Brabender and blended on a lab mill to insurehomogeneity. After mixing, the mixture was then hand rolled using alaboratory mill and cut into pieces or “preps”. To make the centers 11,the preps were then compression molded at about 160° C. (320° F.) forabout 15 minutes. To fabricate the outer layers, the polybutadienerubber material was rolled into flat sheets and the sheets were stackedto form a laminate. The laminate was then compression molded around thecenters as described above. To form the finished golf balls, the coreswere ground and inserted into two cover hemispheres of lithium-sodiumblends of SURLYN®.

[0169] The cover blends used in this example is set forth in Table 2.TABLE 2 Cover Compositions (pph) Example No. 1 2 SURLYN 8320 55% 45%SURLYN 7940 45% 55% Blend Hardness (Shore D) 55 59

Example 2

[0170] The center of the second embodiment, as set forth in Table 3, hasa Shore C hardness of about 77. The first layer is softer than thecenter and has a Shore C hardness of about 73. The second layer issofter than the first layer and has a Shore C hardness of about 71. Thethird layer is softer than the second layer and has a Shore C hardnessof about 68. The cover of the second embodiment golf ball is a hardercover than that used with the first embodiment and includes a blend ofabout 50/50 by weight of a standard sodium ionomer and a standardlithium ionomer. The cover, as described in Table 4, has a Shore Dhardness of about 65 to 70.

[0171] Table 3 sets forth the contents of the golf ball core in thesecond embodiment. The compositions used to prepare the golf ball coreof this embodiment are all in parts per hundred (pph), based on 100parts of polybutadiene.

[0172] In the second embodiment, the center 11 of the core 16 wascompression molded to a diameter of about 1.39 inches and each of thethree layers, 12, 13 and 14 had a thickness of about 0.03 inches. TABLE3 Inner Ball Compositions (pph, based on 100 parts of polybutadiene)Layer No. Center 1 2 3 Polybutadiene 100 100 100 100 Polywate 325 13 1823 26 Vulcup 40KE ® 0.3 0.3 0.3 0.3 Varox 231XL ® 0.5 0.5 0.5 0.6 BaSO₄25 25 26 31 Zinc Diacrylate 47 35 32 30 SR-350 6 2 2 2 Calcium Oxide 0 00 3 Zinc Oxide 6 6 3 0

[0173] To make the core centers 11, preps were made and compressionmolded. To fabricate the outer layers, the polybutadiene rubber materialwas rolled into flat sheets and stacked into a laminate. The laminatewas then compression molded around the centers as described above. Toform the finished golf balls, the cores were ground and inserted intotwo cover hemispheres of standard lithium-sodium blends of SURLYN®.

Example 3

[0174] Table 4 below provides batch compositions for intermediate layerblends for forming the novel multilayer golf balls of the presentinvention. However, it is to be understood that the examples are onlyfor illustrative purposes and in no manner is the present inventionlimited to the specific disclosures therein.

[0175] In particular, batch numbers 2-4 provide intermediate layerblends including NUCREL® 960, HYTREL® 3078, and ZnO used to form theintermediate layers of the golf balls of the present invention. Batchnumber 1 provides a control intermediate layer blend. TABLE 4Intermediate Layer Formulations Flexural Batch % NUCREL ® % HYTREL ® %Modulus Specific # 960 3078 ZnO (psi) Gravity 1 — 80 20 4210 1.27 2 1075 15 5560 1.21 3 20 70 10 7710 1.17 4 30 65 5 7250 1.14

Example 4

[0176] Multilayer golf balls were made having intermediate layers formedfrom the batch compositions set forth in Table 4. Several dozen golfballs were formed using each batch composition and subsequently testedfor compression, spin rate and initial velocity.

[0177] The cores of all of the multilayer balls were formed bycompression molding a blend of the batch formulation set forth in Table5 below. All of the cores had a diameter of 1.39 inches and weremeasured to have compressions ranging from about 45 to about 55 andspecific gravities of from about 1.134 to about 1.146.

[0178] The intermediate layer blends of Table 4 were subsequentlyinjection molded about the cores to form the intermediate layers of theballs having an outer diameter of about 1.51 inches. TABLE 5 CoreFormulation Parts Material Per Hundred Polybutadiene (Shell 1220) 76.0Rubber (Enichem Br40) 24.0 Pigment 0.10 Zinc Diacrylate 24.79 CalciumOxide 2.16 Regrind 6.47 Peroxide (VAROX ®) 0.43 Peroxide (EF-60) (DBDB)0.16 Filler 22.64 Process Oil 1.50

[0179] All of the multilayer balls had a cover composition formed byinjection molding a blend including 50 percent SURLYN® 7940 and 50percent SURLYN® 8140 about the intermediate layers and were subsequentlyfinished using conventional clear coating and buffing techniques. Thefinished golf balls had an outer diameter of about 1.68 inches. Theseballs were tested for initial velocity, compression, cover hardness andCOR, the results of such tests are set forth in Table III below.

[0180] The balls were also tested for spin rate using a True Temper TestMachine configured to strike the balls with a driver and an 8-Iron. Alsotested for comparison purposes were conventional two piece “distance”balls (Titleist® HP2 Distance and Pinnacle® Gold). The test data for allof these balls is set forth in Tables 6-8 below. TABLE 6 Cover² COR³Velocity¹ Compression¹ Weight¹ Hardness (at 125 Ball (ft/s) (Ball) (oz)(Shore D) ft/s) Pinnacle ® 252.5 95 1.605 68 0.809 Gold⁴ Titleist ®253.0 99 1.600 71 0.810 HP2 Distance⁴ Ball 1 251.9 81 1.610 71 0.814Ball 2 252.3 84 1.584 72 0.814 Ball 3 252.2 84 1.588 71 0.813 Ball 4251.9 84 1.590 69 0.810

[0181] TABLE 7 Spin Rates For Driver Launch Spin Club Speed Ball TypeAngle (°) (rpm) (ft/s) Pinnacle ® Gold 9.1 ± 0.3 3032 ± 135 158.6 ± 0.6Titleist ® HP2 Distance 9.0 ± 0.3 2977 ± 60  158.6 ± 1.0 Ball 1 9.1 ±0.5 2973 ± 195 158.4 ± 0.6 Ball 2 9.1 ± 0.5 3001 ± 66  158.9 ± 0.7 Ball3 9.1 ± 0.4 3006 ± 121 158.9 ± 0.8 Ball 4 9.0 ± 0.3 3007 ± 140 159.0 ±0.6

[0182] TABLE 8 Spin Rate For 8-Iron Launch Spin Club Speed Ball TypeAngle (°) (rpm) (ft/s) Pinnacle ® Gold 19.2 ± 0.4 8160 ± 218 116.4 ± 0.1Titleist ® HP2 Distance 19.4 ± 0.5 8375 ± 171 116.3 ± 1.3 Ball 1 19.2 ±0.5 7970 ± 246 116.2 ± 0.7 Ball 3 19.3 ± 0.2 7972 ± 168 116.5 ± 0.9 Ball4 19.4 ± 0.3 7940 ± 171 117.0 ± 1.3

[0183] As shown by results reported in Tables 6-8, golf balls having anintermediate layer including NUCREL® 960, HYTREL® 3078, and ZnO have ahigh initial velocity and low spin rate. Moreover, the balls of thepresent invention have initial velocities approaching those ofconventional two-piece “distance” balls, but have a considerably lowercompression, which provides a much softer feel, more like a wound ball.Still further, these balls are easy to manufacture compared to theconventional wound ball. Thus, these balls provide the advantages of twopiece “distance” balls with low spin rates and high velocity, but alsoprovide a softer feel than such balls.

Example 5

[0184] Multilayer golf balls were made having intermediate layers formedfrom a blend including 20 percent NUCREL® 960, 57 percent HYTREL® 3078,and 23 percent ZnO. This intermediate layer blend was injection moldedabout cores formed from the batch formulation set forth in Table 5. Acover was formed by injection molding a blend of 50 percent SURLYN®7940, 47 percent SURLYN® 8940, and 3 percent SURLYN® 8660 around theintermediate layer and subsequently finishing the balls usingconventional clear coating and buffing techniques.

[0185] The balls were tested for initial velocity, compression, coverhardness and COR, as well as for spin rate when struck by a driver andan 8-Iron using a True Temper Test Machine. The results of such testsare set forth below in Tables 9-11 below. TABLE 9 Cover Velocity¹Compression¹ Weight¹ Hardness² COR³ Specific (ft/s) (Ball) (oz) (ShoreD) (at 125 ft/s) Gravity 251.5 82 1.607 69 0.801 1.27

[0186] TABLE 10 Launch Club Angle (°) Spin (rpm) Club Speed (ft/s)Driver 9.2 ± 0.5 3015 ± 221 160.3 ± 0.7 8 Iron 19.3 ± 0.6  7807 ± 252115.6 ± 0.8

[0187] TABLE 11 Mantle Layer Compositions and Properties % StrainHardness Flex Modulus Tensile Modulus at Sample (Shore D) Resilience (%)(psi) (psi) Break 1A   0% Estane 58091  28 54  1,720 756 563  100%Estane 58861  1B    25% Estane 58091 34 41  2,610 2,438 626    75%Estane 58861 1C    50% Estane 58091 44 31 10,360 10,824 339    50%Estane 58861 1D    75% Estane 58091 61 34 43,030 69,918 149    25%Estane 58861 1E  100% Estane 58091  78 46 147,240  211,288 10   0%Estane 58861  2A  0% Hytrel 5556 40 47  8,500 7,071 527 100% Hytrel4078  2B 25% Hytrel 5556 43 51 10,020 9,726 441 75% Hytrel 4078 2C 50%Hytrel 5556 45 47 12,280 10,741 399 50% Hytrel 4078 2D 75% Hytrel 555648 53 13,680 13,164 374 25% Hytrel 4078 2E 100% Hytrel 5556  48 5212,110 15,231 347  0% Hytrel 4078 3A  0% Hytrel 5556 30 62  3,240 2,078810 100% Hytrel 3078  no break 3B 25% Hytrel 5556 37 59  8,170 5,122 68575% Hytrel 3078 3C 50% Hytrel 5556 44 55 15,320 10,879 590 50% Hytrel3078 3D 75% Hytrel 5556 53 50 19,870 16,612 580 25% Hytrel 3078 3E 100%Hytrel 5556  58 50 24,840 17,531 575  0% Hytrel 3078 4A  0% Hytrel 407846 51 11,150 8,061 597 100% Pebax 4033    4B 25% Hytrel 4078 46 5310,630 7,769 644  75% Pebax 4033  4C 50% Hytrel 4078 45 52  9,780 8,117564  50% Pebax 4033  4D 75% Hytrel 4078 42 53  9,310 7,996 660  25%Pebax 4033  4E 100% Hytrel 4078  40 51  9,250 6,383 531  0% Pebax 40335A  0% Hytrel 3078 77 50 156,070  182,869 9  100% Estane 58091  5B 25%Hytrel 3078 65 48 87,680 96,543 33    75% Estane 58091 5C 50% Hytrel3078 52 49 53,940 48,941 102    50% Estane 58091 5D 75% Hytrel 3078 3554 12,040 6,071 852    25% Estane 58091 5E 100% Hytrel 3078  29 50 3,240 2,078 810   0% Estane 58091  no break 6A 100% Kraton 1921  29 5924,300 29,331 515   0% Estane 58091     0% Surlyn 7940 6B  50% Kraton1921  57 49 56,580 — 145    50% Estane 58091    0% Surlyn 7940 6C  50%Kraton 1921  56 55 28,290 28,760 295   0% Estane 58091   50% Surlyn7940  7A 33.3% Pebax 4033   48 50 41,240 30,032 294 33.3% Estane 58091 33.3% Hytrel 3078   7B  30% Pebax 4033  48 50 30,650 14,220 566    40%Estane 58091 10% Hytrel 3078 7C  20% Pebax 4033  41 54 24,020 16,630 512   40% Estane 58091 40% Hytrel 3078

[0188] While it is apparent that the illustrative embodiments of theinvention herein disclosed fulfill the objectives stated above, it willbe appreciated that numerous modifications and other embodiments may bedevised by those skilled in the art. Therefore, it will be understoodthat the appended claims are intended to cover all such modificationsand embodiments which come within the spirit and scope of the presentinvention.

What is claimed is:
 1. A golf ball comprising: a center; a cover; and alaminate, wherein the laminate comprises: a plurality of layerscomprising at least a first layer comprising at least one thermoplasticmaterial and at least a second layer comprising at least one thermosetmaterial.
 2. The golf ball of claim 1, wherein the first layer isadjacent the center and the at least one thermoplastic materialcomprises dynamically vulcanized thermoplastic elastomers,functionalized styrene-butadiene elastomers, thermoplastic rubbers,thermoplastic urethanes, metallocene polymers, ionomer resins, or blendsthereof.
 3. The golf ball of claim 1, wherein the first layer has afirst hardness and the center has a center hardness, wherein the firsthardness is greater than the center hardness.
 4. The golf ball of claim1, wherein the center has a center hardness, the first layer has a firsthardness, and the second layer has a second hardness, and wherein thefirst hardness is less than the center hardness.
 5. The golf ball ofclaim 1, wherein the second layer is adjacent the cover and the at leastone thermoset material has a flexural modulus of about 50,000 psi orgreater.
 6. The golf ball of claim 1, wherein the at least one thermosetmaterial comprises polybutadiene.
 7. The golf ball of claim 1, whereinthe cover comprises at least one layer formed of a material having aflexural modulus of about 50,000 psi or less.
 8. The golf ball of claim1, further comprising a third layer disposed in between the first layerand the second layer, wherein the third layer has a third hardnessgreater than the first hardness.
 9. The golf ball of claim 4, whereinthe laminate further comprises a third layer disposed in between thefirst layer and the second layer, wherein the third layer has a thirdhardness less than the first hardness.
 10. The golf ball of claim 9,wherein the first hardness is from about 70 to about 75 Shore C, thesecond hardness is from about 75 to about 80 Shore C, and the thirdhardness is from about 72 to about 77 Shore C.
 11. The golf ball ofclaim 1, wherein the cover is formed of a composition comprising atleast one castable reactive liquid material.
 12. The golf ball of claim11, wherein the at least one castable reactive liquid material comprisescast polyurethane.
 13. The golf ball of claim 1, wherein the pluralityof patterns are substantially figure 8-shaped.
 14. The golf ball ofclaim 1, wherein the laminate comprises a plurality of layers, eachlayer having a thickness of about 0.1 inches or less.
 15. The golf ballof claim 14, wherein the thickness is about 0.05 inches or less.
 16. Thegolf ball of claim 1, wherein the thermoplastic material has a flexuralmodulus of about 10,000 psi or less.
 17. A golf ball comprising: acenter; a cover; and a laminate, wherein the laminate comprises: aplurality of layers comprising at least a first layer comprising atleast one thermoplastic material and at least a second layer comprisingat least one thermoset material, wherein the plurality of layers aresubstantially figure 8-shaped.
 18. The golf ball of claim 16, whereineach layer of the laminate has a thickness of about 0.1 inches or less.19. The golf ball of claim 16, wherein the first layer has a firsthardness and the center has a center hardness, wherein the firsthardness is greater than the center hardness.
 20. The golf ball of claim16, wherein the second layer is adjacent the cover and the at least onethermoset material has a flexural modulus of about 50,000 psi orgreater.